GB 2 118 096 (Hill and Yule), U.S. Re. Pat. No. 37,186 (Hill) reissued from U.S. Pat. No. 4,673,609 and U.S. Pat. No. 4,925,705 (Hill) describe methods of printing with exact registration, in which layers of cured ink are removed from areas of a substrate to leave exactly superimposed layers of ink on the remaining areas of the substrate. Methods referred to in these patents as the “direct” and “stencil” methods require an “ink fracture mechanism” to be formed around the desired “silhouette pattern” or “print pattern”, typically of dots or lines. UV-curing ink is not disclosed in these patents, and typical UV-curing screenprinting ink has been found to be unsuitable for these methods. That is because the “chemical cross-linking” which occurs upon UV-curing creates a “membrane strength” or tensile capability in the cured ink layer(s) which prevents ink fracture or which prevents a “clean” ink fracture along the desired boundary of each area of the print pattern. Thus, any resultant fracture is irregular and inaccurate, with ink ‘flaps’ projecting into areas outside the desired or intended print pattern.
U.S. Pat. No. 6,267,052 “Printing with Differential Receptivity” (Hill and Godden), discloses methods of printing with lack of registration and printing with exact registration, together with seven methods of exactly superimposing an image “design layer” onto a pre-printed “print pattern” which partially covers a substrate. One of those seven methods is Method 3, “Conventional Printed Ink or Digital Ink Jet Differential Adhesion Method.” According to Method 3, the ink adheres to the print pattern to form a durable image material but does not form a durable image material on the unprinted portions of the substrate. That method can be used for a variety of purposes, including manufacturing one-way vision panels according to U.S. Re. 37,186 or other products in which areas of the substrate are required to be printed with exactly superimposed layers of ink. U.S. Pat. No. 6,267,052 discloses alternative inks that are suitable for forming a “design layer” by means of Method 3, including water-based inks, catalytic inks, and solvent-based inks. UV-curable inks are not disclosed in that patent, and UV-curable inks are believed never to have been disclosed or used in connection with Method 3. U.S. Pat. No. 6,267,052 also discloses the use of self-adhesive vinyl stripes to form a “print pattern”, and applying an “application tape” or “overlaminate” to imaged vinyl stripes to enable their application to a window.
U.S. Pat. No. 6,210,776 discloses what is referred to as the “Through Combination” method of managing the normal lack of registration in the printing of superimposed layers which can arise when making panels. UV-curing screen ink has been used to make such panels according to Method 3 under the trademark Overlap Registration System™, the panels being sold under the trademark Contra Vision SCREENLINE™, both trademarks being owned by Contra Vision Ltd, a UK company. The Through Combination method does not utilize differential receptivity or differential adhesion or removal of unwanted ink.